Methods for producing strain sensors on turbine components

ABSTRACT

Methods for manufacturing strain sensors on turbine components include providing a turbine component comprising an exterior surface, depositing a ceramic material onto a portion of the exterior surface, and ablating at least a portion of the ceramic material to form a strain sensor comprising at least two reference points.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to strain sensors and, morespecifically, to methods for producing ceramic strain sensors on turbinecomponents for high temperature applications.

In gas turbine engines, such as aircraft engines for example, air isdrawn into the front of the engine, compressed by a shaft-mountedrotary-type compressor, and mixed with fuel. The mixture is burned, andthe hot exhaust gases are passed through a turbine mounted on a shaft.The flow of gas turns the turbine, which turns the shaft and drives thecompressor and fan. The hot exhaust gases flow from the back of theengine, driving it and the aircraft forward.

During operation of gas turbine engines, the temperatures of combustiongases may exceed 3,000° F., considerably higher than the meltingtemperatures of the metal parts of the engine which are in contact withthese gases. Operation of these engines at gas temperatures that areabove the metal part melting temperatures may depend in part one or moreprotective coatings and/or on supplying a cooling air to the outersurfaces of the metal parts through various methods. The metal parts ofthese engines that are particularly subject to high temperatures, andthus require particular attention with respect to cooling, are the metalparts forming combustors and parts located aft of the combustor.

Moreover, the turbine components may experience stress and/or strainfrom various forces over its operational lifecycle. While various toolsmay be utilized to measure imparted stress and strain in relativelystandard environments, the turbine components in turbine engines mayexperience hotter and/or more corrosive working conditions that may beunsuitable for such measurement tools.

Accordingly, alternative strain sensors and methods for producingceramic strain sensors on turbine components would be welcome in theart.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a method for manufacturing a strain sensor on aturbine component is disclosed. The method includes providing a turbinecomponent comprising an exterior surface, and, depositing a ceramicmaterial onto a portion of the exterior surface. The method furtherincludes ablating at least a portion of the ceramic material using alaser to form a strain sensor comprising at least two reference points.

In another embodiment, a method of monitoring a turbine component isdisclosed. The method includes providing a turbine component comprisingan exterior surface, depositing a ceramic material onto a portion of theexterior surface, and ablating at least a portion of the ceramicmaterial using a laser to form a strain sensor comprising at least tworeference points. The method further includes measuring a seconddistance between a first of the at least two reference points of thestrain sensor and a second of the at least two reference points of thestrain sensor at a second time internal. Finally, the method includescomparing the second distance to a first distance between the first ofthe at least two reference points of the strain sensor and the second ofthe at least two reference points of the strain sensor from a first timeinterval.

In yet another embodiment, a turbine component is disclosed. The turbinecomponent includes an exterior surface, and, a strain sensor depositedon a portion of the exterior surface, wherein the strain sensorcomprises a partially ablated ceramic material comprising at least tworeference points.

These and additional features provided by the embodiments discussedherein will be more fully understood in view of the following detaileddescription, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments set forth in the drawings are illustrative and exemplaryin nature and not intended to limit the inventions defined by theclaims. The following detailed description of the illustrativeembodiments can be understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is an exemplary turbine component comprising a strain sensoraccording to one or more embodiments shown or described herein;

FIG. 2 is an exemplary strain sensor according to one or moreembodiments shown or described herein;

FIG. 3 is cross section of ceramic material deposited on a turbinecomponent according to one or more embodiments shown or describedherein;

FIG. 4 is a cross section of another exemplary strain sensor on aturbine component according to one or more embodiments shown ordescribed herein;

FIG. 5 is a cross section of yet another strain sensor on a turbinecomponent according to one or more embodiments shown or describedherein;

FIG. 6 is a cross section of even yet another strain sensor on a turbinecomponent according to one or more embodiments shown or describedherein;

FIG. 7 is an exemplary method for manufacturing a strain sensor on aturbine component according to one or more embodiments shown ordescribed herein; and,

FIG. 8 is an exemplary method for monitoring a turbine componentaccording to one or more embodiments shown or described herein.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Referring now to FIG. 1, a turbine component 10 is illustrated with astrain sensor 40 comprising ceramic material 30 deposited on a portionof the turbine component's exterior surface 11, wherein at least aportion of the ceramic material is ablated by a laser.

The turbine component 10 can comprise a variety of specific componentssuch as those utilized in high temperature applications (e.g.,components comprising nickel or cobalt based superalloys). For example,in some embodiments, the turbine component 10 may comprise a combustioncomponent or hot gas path component. In some particular embodiments, theturbine component 10 may comprise a bucket, blade, vane, nozzle, shroud,rotor, transition piece or casing. In other embodiments, the turbinecomponent 10 may comprise any other component of a turbine such as acomponent for a gas turbine, industrial gas turbine, steam turbine orthe like.

The turbine component 10 has an exterior surface 11. As should beappreciated herein, the exterior surface 11 may have one or more exposedportions 12 and can include any area suitable for the location of astrain sensor 40 for the subsequent capturing of strain measurements. Asused herein, “exposed portion” refers to an area of the exterior surface11 that is, at least initially, absent of ceramic coatings (e.g.,thermal barrier coating or the like). In such embodiments, the absenceof ceramic coatings may allow for the base metal/alloy to be morevisibly identifiable when analyzing the at last two reference points 41and 42 of the strain sensor 40 as should be appreciated herein. Asshould also become appreciated herein, in some embodiments, the exposedportion 12 may subsequently be coated with a supplemental material suchas a visually contrasting material 35 (as illustrated in FIGS. 4 and 5)that is visually distinct from the strain sensor 40.

Referring now to FIGS. 1-6, the ceramic material 30 is deposited on aportion of the exterior surface 11 of the turbine component 10 (FIG. 3).A portion of the ceramic material 30 is subsequently ablated by a laser25 (FIG. 4) for form the strain sensor 40. The strain sensor 40generally comprises at least two reference points 41 and 42 that can beused to measure the distance D between said at least two referencepoints 41 and 42 at a plurality of time intervals. As should beappreciated to those skilled in the art, these measurements can helpdetermine the amount of strain, strain rate, creep, fatigue, stress,etc. at that region of the turbine component 10. The at least tworeference points 41 and 42 can be disposed at a variety of distances andin a variety of locations depending on the specific turbine component 10so long as the distance D there between can be measured. Moreover, theat least two reference points 41 and 42 may comprise dots, lines,circles, boxes or any other geometrical or non-geometrical shape so longas they are consistently identifiable and may be used to measure thedistance D there between.

The strain sensor 40 comprises a ceramic material that is deposited by adeposition apparatus 20 and then partially ablated by a laser 25. Morespecifically, the strain sensor 40 itself comprises any ceramic materialor materials suitable for deposition (such as utilizing a ceramic powderthrough an automated additive manufacturing process), ablation (such asby a laser 25), and optical recognition (such as for measuring thedistance D between the at least two reference points 41 and 42 asdiscussed above). The ceramic strain sensor 40 may provide increasedtemperature survivability compared to other strain sensor materials. Forexample, in some embodiments, the ceramic material 30 may comprise athermal barrier coating such as yttria-stabilized zirconia (alsoreferred to as YSZ). In such embodiments, the YSZ may comprise, forexample, YSZ-D111. In even some embodiments, the strain sensor 40 maycomprise a metallic bond coat and/or thermally grown oxide to assist inthe deposition of the ceramic top coat (e.g., YSZ). While someparticular turbine components 10 (or at least particular locationsthereon) may not experience the elevated temperatures to require thermalbarrier coatings, such utilization for the strain sensor 40 may ensureits longevity where other strain sensor materials (e.g., polymericmaterials, chemical dyes, etc.) could potentially break down anddisappear from the relatively harsh environment.

In even some embodiments, the strain sensor 40 may comprise a visuallycontrasting material 35 in addition to the ceramic material 30. As usedherein, “visually contrasting material” 35 refers to any material thatvisually contrasts with the ceramic material such as through differentcolors or patterns. The visually contrasting material 35 may helpfacilitate identification of the first and second reference points 41and 42 of the strain sensor 40 by visually highlighting their locationsfor an operator and/or machine. The visually contrasting material 35 maycomprise any additional metal, alloy, ceramic or the like that cansimilarly survive on the turbine component 10 during operation. Forexample, in some embodiments, the visually contrasting material 35 maycomprise a doped version of the ceramic material 30 that changes itscolor.

In some embodiments, such as that illustrated in FIG. 5, the visuallycontrasting material 35 may be deposited directly within the negativespace 45 of the strain sensor (i.e., where the ceramic material 30 wasablated by the laser 25) such that the ceramic material 30 and thevisually contrasting material 35 form one substantial layer. In evensome embodiments, such as that illustrated in FIG. 6, the visuallycontrasting material 35 may be deposited directly on the turbinecomponent 10 and then the ceramic material 30 may be deposited on top ofthe visually contrasting material 35.

In some embodiments, the strain sensor 40 itself may comprise any otherdetectable type of contrasting characteristic that sets it apart fromthe underlying turbine component 10. For example, the strain sensor 40may comprise a different height, roughness, pattern or the like, mayemit distinct energy (e.g., photoluminescence, radiation, etc.), or maycomprise any other differentiating characteristic compared to theturbine component 10. These and similar embodiments may facilitate theidentification of, and measurements between, the first and secondreference points 41 and 42 such as through surface metrology, energyemission analysis or the like.

The ceramic material 30 may be deposited using any deposition apparatus20 suitable for depositing with high enough precision to form the strainsensor 40 as should be appreciated herein. For example, in someembodiments, the deposition apparatus 20 may comprise an aerosol jetcoater (e.g., Aerosol Jen and LENS systems from Optomec), MicroDispensing Machine (e.g., Micropen or 3Dn from Ohcraft, Inc. or nScrypt,Inc), MesoPlasma from MesoScribe Technologies, Inc., plasma spray, orany other suitable apparatus or combinations thereof. In even someembodiments, the ceramic material 30 may be airbrushed so long assuitable thickness levels can be obtained.

The ceramic material may then be ablated by any suitable laser. As usedherein, “ablate” (and variations thereof) refers to any material removalvia the laser 25. The laser can comprise any suitable power andconfiguration to ablate enough ceramic material to form the at least tworeference points 41 and 42. For example, in some embodiments the laser25 may comprise a power of from about 40 watts to about 80 watts. Ineven some embodiments, the laser 25 may comprise a power of less than 40watts such as, for example, an 8 Watt YVO4 crystal YAG laser. In someembodiments, the laser 25 may comprise a pulsed laser. In even someembodiments, the laser 25 may ablate the ceramic material 30 viamultiple passes. Such factors may facilitate the ablation of ceramicmaterial 30 without substantially burning the underlying turbinecomponent 10.

In some embodiments, the ceramic material 30 may be at least partiallycured prior to ablation. Such curing may help ensure the ceramicmaterial 30 is stable on the exterior surface 11 of the turbinecomponent 10 prior to ablation. Curing may occur at any suitabletemperature and for any suitable time such as, for example, at fromabout 50° C. to about 100° C. for at least about 2 hours. It should beappreciated, however, that any other suitable curing conditions may alsobe utilized.

As discussed herein, the strain sensor 40 may be utilized in conjunctionwith different recognition techniques to help determine one or moredistance measurements between at least the first and second referencepoints 41 and 42. Accordingly, the laser 25 may ablate the ceramicmaterial 30 with a suitable resolution to define a strain sensor 40 thatcomprises at least first and second reference points 41 and 42 that areidentifiable, such as optically by a machine or individual. In someembodiments, the laser 25 may ablate the ceramic material 30 with aresolution of at least 15 microns. In even some embodiments, the laser25 may ablate the ceramic material 30 with a submicron resolution.

In some embodiments, the ceramic material 30 (and potentially anyvisually contrasting material 35) may undergo one or more additionalcuring and/or sintering stages, either prior to or after ablation. Anycuring and/or sintering may depend on the specific type of ceramicmaterial 30 and can comprise any suitable temperature and time tosubstantially solidify the strain sensor 40 onto the exterior surface 11of the turbine component 10. In some particular embodiments, the ceramicmaterial 30 may be at least partially cured prior to ablation and thenfully sintered after ablation.

As best illustrated in FIGS. 2-6, the strain sensor 40 may comprise avariety of different configurations and cross-sections such as byincorporating a variety of differently shaped, sized, and positionedreference points 41 and 42. For example, as illustrated in FIG. 2, thestrain sensor 40 may comprise a variety of different reference pointscomprising various shapes and sizes. Such embodiments may provide for agreater variety of distance measurements D such as between the outermost reference points (as illustrated), between two internal referencepoints, or any combination there between. The greater variety mayfurther provide a more robust strain analysis on a particular portion ofthe turbine component 10 by providing strain measurements across agreater variety of locations.

Furthermore, the dimensions of the strain sensor 40 may depend on, forexample, the turbine component 10, the location of the strain sensor 40,the targeted precision of the measurement, deposition technique,ablation technique, and optical measurement technique. For example, insome embodiments, the strain sensor 40 may comprise a length and widthranging from less than 1 millimeter to greater than 300 millimeters.Moreover, the strain sensor 40 may comprise any thickness that issuitable for deposition, ablation and subsequent optical identificationwithout significantly impacting the performance of the underlyingturbine component 10. For example, in some embodiments, the strainsensor 40 may comprise a thickness of less than from about 0.1millimeters to greater than 1 millimeter. In some embodiments, thestrain sensor 40 may have a substantially uniform thickness. Suchembodiments may help facilitate successful ablation and more accuratemeasurements for subsequent strain calculations between the first andsecond reference points 41 and 42.

In some embodiments, the strain sensor 40 may comprise a positivelydeposited square or rectangle (such that surrounding material wasablated) wherein the first and second reference points 41 and 42comprise two opposing sides of said square or rectangle. In otherembodiments, the strain sensor 40 may comprise at least two depositedreference points 41 and 42 separated by negative space 45 (i.e., an areain which ceramic material 30 was ablated). The negative space 45 maycomprise, for example, an exposed portion 12 of the exterior surface 11of the turbine component 10. Alternatively or additionally, the negativespace 45 may comprise a subsequently deposited visually contrastingmaterial 35 that is distinct from the material of the at least tworeference points 41 and 42.

As illustrated in FIG. 2, in even some embodiments, the ceramic material30 of the strain sensor 40 may be ablated to form a unique identifier 47(hereinafter “UID”). The UID 47 may comprise any type of barcode, label,tag, serial number, pattern or other identifying system that facilitatesthe identification of that particular strain sensor 40. In someembodiments, the UID 47 may additionally or alternatively compriseinformation about the turbine component 10 or the overall turbine thatthe strain sensor 40 is deposited on. The UID 47 may thereby assist inthe identification and tracking of particular strain sensors 40, turbinecomponents 10 or even overall turbines to help correlate measurementsfor past, present and future operational tracking.

The strain sensor 40 may thereby be deposited in one or more of avariety of locations of various turbine components 10. For example, asdiscussed above, the strain sensor 40 may be deposited on a bucket,blade, vane, nozzle, shroud, rotor, transition piece or casing. In suchembodiments, the strain sensor 40 may be deposited in one or morelocations known to experience various forces during unit operation suchas on or proximate airfoils, platforms, tips or any other suitablelocation. Moreover, since the strain sensor 40 comprises a ceramicmaterial, the strain sensor 40 may be deposited in one or more locationsknown to experience elevated temperatures (wherein strain sensorscomprising other materials may corrode and/or erode). For example thestrain sensor 40 comprising ceramic material may be deposited on a hotgas path or combustion turbine component 10.

In even some embodiments, multiple strain sensors 40 may be deposited ona single turbine component 10 or on multiple turbine components 10. Forexample, a plurality of strain sensors 40 may be deposited on a singleturbine component 10 (e.g., a bucket) at various locations such that thestrain may be determined at a greater number of locations about theindividual turbine component 10. Alternatively or additionally, aplurality of like turbine components 10 (e.g., a plurality of buckets),may each have a strain sensor 40 deposited in a standard location sothat the amount of strain experienced by each specific turbine component10 may be compared to other like turbine components 10. In even someembodiments, multiple different turbine components 10 of the sameturbine unit (e.g., buckets and vanes for the same turbine) may eachhave a strain sensor 40 deposited thereon so that the amount of strainexperienced at different locations within the overall turbine may bedetermined

Referring additionally to FIG. 7, a method 100 is illustrated formanufacturing a strain sensor 40 on a turbine component 10. The method100 first comprises providing a turbine component 10 in step 110. Asdiscussed herein, the turbine component 10 can comprise any componenthaving an exterior surface 11. The method further comprises depositing aceramic material 30 onto a portion of the exterior surface 11 in step120. The method then comprises ablating at least a portion of theceramic material 30 to form the strain sensor 40 in step 130. As alsodiscussed herein, the strain sensor 40 formed via the ablation comprisesat least two reference points 41 and 42. In some particular embodiments,the at least two reference points 41 and 42 may be at least partiallyseparated by an exposed portion of the exterior surface 11. In someembodiments, ablation in step 130 may occur prior to sintering theceramic material 30 of the strain sensor 40. In such embodiments, thestrain sensor 40 may be partially cured such that it is in a greenstate, ablated by a laser, and then fully sintered. In otherembodiments, the strain sensor 40 may be ablated after the ceramicmaterial 30 is fully sintered. Furthermore, in some of theseembodiments, the method 100 may further comprise depositing a visuallycontrasting material 35 in the exposed portion in step 140 to assist inthe identification of the at least two reference points 41 and 42.Method 100 may be repeated to produce multiple strain sensors 40 on thesame turbine component 10, multiple strain sensors 40 on differentturbine components 10, or combinations thereof.

Referring additionally to FIG. 8, another method 200 is illustrated formonitoring a turbine component 10. Similar to method 100, method 200further comprises depositing a ceramic material 30 onto a portion of theexterior surface 11 in step 220. The method 200 then comprises ablatingat least a portion of the ceramic material 30 to form the strain sensor40 in step 230. Method 200 further comprises determining a firstdistance D between a first 41 and a second 42 of the at least tworeference points of the strain sensor 40 in step 240. In someembodiments, determining the first distance D can be accomplishedthrough measuring. In even some embodiments, such as when ablation ofthe ceramic material 30 is accomplished with high resolution,determining the first distance D may be accomplished by simply knowingthe distance based on the ablation specifications of the strain sensor40 in step 220. Method 200 then comprises utilizing the turbinecomponent 10 in a turbine in step 250. Subsequently, method 200comprises measuring a second distance D between the same first 41 andsecond 42 of the at least two reference points of the strain sensor 40in step 260. Finally, method 200 comprises comparing the first distanceto the second distance in step 270. By comparing the distances measuredat different times in step 270, the strain experienced by the turbinecomponent 10 at the location of the strain sensor 40 may be determined

It should now be appreciated that ceramic strain sensors may bedeposited on turbine components. The ceramic strain sensors mayfacilitate the monitoring of the turbine components performance whilewithstanding the potentially harsh operating conditions.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A method for manufacturing a strain sensor on a turbine component, the method comprising: providing a turbine component comprising an exterior surface; depositing a ceramic material onto a portion of the exterior surface using a deposition apparatus; and, ablating at least a portion of the ceramic material using a laser to form a strain sensor comprising at least two reference points, and further comprising depositing a visually contrasting material where the ceramic material was ablated, whereby the visually contrasting material visually highlights identification of the first and second reference points of the strain sensor by their locations.
 2. The method of claim 1, further comprising sintering the ceramic material before ablating at least a portion of the ceramic material.
 3. The method of claim 1, further comprising sintering the ceramic material after ablating at least a portion of the ceramic material.
 4. The method of claim 1, wherein the turbine component comprises a nickel or cobalt based superalloy.
 5. The method of claim 1, wherein the ceramic material comprises yttria-stabilized zirconia.
 6. The method of claim 1, wherein ablating at least a portion of the ceramic material comprises multiple passes of the laser.
 7. The method of claim 1, wherein ablating at least a portion of the ceramic material further comprises forming a unique identifier.
 8. The method of claim 1, further comprising depositing additional ceramic material onto a second portion of the exterior surface using the deposition apparatus, and ablating at least a portion of the additional ceramic material using the laser to form a second strain sensor comprising at least two reference points.
 9. A method comprising: providing a turbine component comprising an exterior surface; depositing a ceramic material onto a portion of the exterior surface; ablating at least a portion of the ceramic material using a laser to form a strain sensor comprising at least two reference points; depositing a visually contrasting material where the ceramic material was ablated; monitoring the turbine component, the monitoring comprising: measuring a second distance between a first of the at least two reference points of the strain sensor and a second of the at least two reference points of the strain sensor at a second time internal; and, comparing the second distance to a first distance between the first of the at least two reference points of the strain sensor and the second of the at least two reference points of the strain sensor from a first time interval; whereby the depositing a visually contrasting material where the ceramic material was ablated visually highlights identification of the first and second reference points of the strain sensor by their locations.
 10. The method of claim 9, further comprising utilizing the turbine component in a turbine between the first and second time intervals.
 11. The method of claim 9, wherein the turbine component comprises a nickel or cobalt based superalloy.
 12. The method of claim 9, wherein the ceramic material comprises yttria-stabilized zirconia.
 13. A turbine component comprising: an exterior surface; and, a strain sensor deposited on a portion of the exterior surface, the strain sensor comprising partially ablated ceramic material comprising at least two reference points; visually contrasting material at least partially provided where the ceramic material was ablated; wherein the at least two reference points are at least partially separated by the visually contrasting material; and wherein the visually contrasting material visually highlights identification of the first and second reference points of the strain sensor by their locations.
 14. The turbine component of claim 13, wherein the turbine component comprises a nickel or cobalt based superalloy.
 15. The turbine component of claim 13, wherein the turbine component comprises a hot gas path or combustion component.
 16. The turbine component of claim 13, wherein the ceramic material comprises yttria-stabilized zirconia. 